Method of and apparatus for reducing the thickness of metal



Aug. 4, 1964 SAXL 3,143,010

METHOD OF AND APPARATUS FOR REDUCING THE THICKNESS 0F METAL Filed Sept. 15, 1959 4 Sheets-Sheet 1 FIG. I.

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K. SAXL 3,143,010 METHOD OF AND APPARATUS FOR REDUCING THE THICKNESS OF METAL Aug. 4, 1964 4 Sheets-Sheet 2 Filed Sept. 15, 1959 FIG.

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METHOD OF AND APPARATUS FOR REDUCING THE THICKNESS OF METAL Filed Sept. 15, 1959 4 Sheets-Sheet 3 I Y 7 r 20 24 l i I -22 I 23/ (-1 26 1: Ii 29.

FIG. 3. //vv/vr0/? Aug. 4, 1964 K. SAXL 10 METHOD OF AND APPARATUS FOR REDUCING THE THICKNESS OF METAL Filed Sept. 15, 1959 4 Sheets-Sheet 4 INVENTOR ATTORNEY? 3,143,010 METHOD OF AND APPARATUS FOR REDUCING THE THICKNESS F METAL Karel Saxl, Sutton Coldfield, England, assignor to Imperial Chemical Industries Limited, London, England, a corporation of Great Britain Filed Sept. 15, 1959, Ser. No. 840,130 Claims priority, application Great Britain Sept. 17, 1958 9 Claims. (Cl. 80-40) This invention is concerned with a method of and apparatus for reducing the thickness of metal in plate or strip or slab form.

In the applicants prior application Serial No. 784,524, now US. Patent 3,103,139, there is described a method of reducing the thickness of metal in which the metal is progressively moved between a pair of freely-rotatable work-rolls which swing forwardly and backwardly in synchronism with each other in such manner that the metal is reduced in thickness between the work-rolls during swinging movement of the work-rolls in one direction but undergoes substantially no reduction throughout swinging movement of the work-rolls in the other direction.

The applicant has now found that in a modification of the method deformation of the metal can be carried out on both forward and backward strokes.

According to this invention, a method of reducing the thickness of metal comprises advancing the metal between and beyond a pair of freely rotatable work-rolls disposed on opposite sides of the metal and subjecting the metal to the rolling action of the pair of freely-rotatable workrolls, the rolls moving in synchronism in a pendulum-like manner at a high speed and substantially remaining in contact with the metal throughout their movement.

Preferably, but not necessarily, the metal is advanced continuously between and beyond the work-rolls. As a consequence of the work-rolls being freely-rotatable the metal is advanced between and beyond the work-rolls at a rate which is fully independent of the frequency of oscillation of the rolls, the permissible rate of advance ranging from zero to the maximum imposed by the process limitations. This feature, which gives considerable flexibility to the process, is of particular importance when dealing with wide ranges of hardness of materials or with complicated sections etc. as described later and also in starting the process.

In the case of reducing strip or plate it is necessary to hold the metal in tension at least over the area being reduced in order to prevent buckling of the strip or plate.

Whilst the apparatus described in the applicants earlier application can be used for carrying out the method in accordance with the invention, some modification of the mode of operation is necessary in order to maintain the work-rolls in contact with the metal. In such modification, the device for moving the pivots on which the swingable arms are mounted is not operated so that the arms swing about pivots which are fixed. The path of the work-rolls is thus the same are for both forward and backward strokes.

According to a feature of the invention an apparatus for carrying out the method of the invention comprises a frame, a pair of opposite swingable arms, the free ends of which are adjacent, a freely-rotatable work-roll mounted on the free end of each arm, and mechanical driving means operable so as to cause swinging of the arms forwardly and backwardly in synchronism with each other.

Optionally, resilient means operable to relieve the mill strain during part of the swinging movement by introducing a resilient device between the frame and the pivot of the swingable arms may be incorporated in the mill structure. Such a device may take the form of springs located between the screw-down gear and that part of the apparatus upon which the pivot of one of the swingable arms is mounted. When such a device is fitted a small but controllable amount of movement of the pivot may occur during the stroke but the work-rolls remain in contact with the work-piece during the whole of each stroke.

When rolling plate or strip in an apparatus in accordance with the invention, the plate or strip may be conveniently held in tension during rolling by passing the plate or strip through a pair of pinch rolls before it enters the mill and coiling the reduced metal on a conventional coiling apparatus. Such a method is suitable when the metal being reduced is in sufliciently long lengths but, for the reduction of slabs, a modification is necessary because of the comparatively short length of a slab.

The material, either in slab or strip form has to be forced through the mill either by pushing, for instance by pinch rolls, on the ingoing side or by pulling on the outgoing side.

In some cases it is an advantage to arrange that the resultant of forces acting on the material is always directed against the feed. This can be arranged for instance by causing the rolls to swing through an are on the ingoing side of the centre-line connecting the pivots sothat the axes of the rolls do not reach the centre-line during their swing. In this manner there is always a component of the rolling force pushing the material against the direction of feed. Thus it is possible to roll slabs or strip-plate without holding the metal in tension between pinch rolls as, for example, when the end of the slab or strip-plate has passed through the pinch rolls on the ingoing side and is being pulled through the mill by the coiler. Without the pushing effect of the component of force referred to above, it is possible that the metal could be severely buckled or dragged through the mill by the work-rolls.

In rolling a succession of slabs of similar thickness, the hot slabs are arranged with their ends abutting and advanced between the rolls. The transition from one slab to the next is quite smooth and there is no necessity to weld the ends of the slabs together.

As the abutting ends pass between the work-rolls, the rolls pass forwards and backwards across the junction and as a result there may be a tendency for the ends of the hot metal to become welded together during the rolling operation. This no disadvantage, for it enables the strip to be continuously coiled.

The apparatus for rolling slabs may be arranged with a vertical or inclined pass line so that the metal being reduced travels upwardly, the slab being below the rolls. In such a case, the amplitude of oscillation ofthe rolls can be greater than when the pass line is horizontal, since, to some extent gravity may be used as the force acting in the opposite direction to the feed of material. Alternatively, with a vertical pass line, the material to be reduced can be located above the work-rolls, so that the apparatus could be positioned beneath a continuous casting machine, the freshly solidified metal being rolled shortly after emerging from the casting machine. The resilient device already referred to may be incorporated in an apparatus for the reduction of slab.

Work-rolls for producing strip from plate or slab are plain rolls but, as with conventional rolling practice, the contour of the rolls may be modified so as to produce a shape of desired section. Thus the rolls may be grooved so as to produce a desired cross-section, e.g. finned or flanged strip, or angle, channel or I-beam. 'In such cases, it may not be possible to coil the resulting section, and

the reduced metal may be withdrawn, if necessary, by oth-' er means. Lateral spread of the strip may be prevented by providing the rolls with flanges, the'height of which is less than half the thickness of the rolled strip, so positioned as to engage the edges of the strip at the nipof the rolls. This design of rolls ensures that the strip produced has good edges.

By operating a modification of the method in accordance with the invention, it is possible to produce strip the thickness of which tapers along its length. This is achieved by operating the screw-down gear at a given rate during the reducing operation. In a further modification, strip having varying thickness along its length can be produced by varying the minimum separation of the rolls as a result of moving the pivots of the swingable arms towards and away from each other by operation of the screw-down gear whilst the metal is being reduced. Strip having thick and thin portions alternatively at right angles tothe axis of the strip or strip increasing in thickness in steps can be made by these modifications.

The method according to the invention is particularly suitable for the reduction of thick slab since very large reductions, e.g. 90%, are possible without reheating and thus permits slab to be reduced to strip in a single pass. If desired, the strip so produced may be subsequently cold rolled to final dimensions in a conventional rolling mill.

An apparatus for reducing the thickness of metal in accordance with one embodiment of the invention is illustrated in the accompanying drawings, of which:

FIGURE 1 is a schematic view of the apparatus and ancillary equipment;

FIGURE 2 is a side elevational view of part of the apparatus;

FIGURE 3 is a front elevational view, partly in section, of the apparatus;

FIGURE 4 is a detail section view of the resilient connection of the pendulum arms to the frame of the apparatus, showing a screwdown gear; and

FIGURE 5 is a detail view of rollers. according to this invention with flanges for controlling lateral spread of the metal strip.

Referring to FIGURE 1 of the accompanying drawings, a strip of metal 1, the thickness of which is to be reduced, is fed between a pair of feed rollers 2, 3 and through a heating chamber 4 and the heated metal is then fed between a pair of freely-rotatable work-rolls 5, 6 which act on opposite sides of the strip. The reduced strip passes between a pair of pinch rollers 7, 8, another pair of guide rollers 9, 10 and is wound upon a coiling drum 11.

The freely-rotatable work-rolls are mounted on end portions of compound pendulums 12, 13. The compound pendulum 12 oscillates during operation of the apparatus by lever 14 which is connected to a driven crank 15.

Similarly, the compound pendulum 13 is oscillated in synchronism with compound pendulum 12 by lever 16 which is connected to a driven crank 17.

Thus, as the compound pendulums swing from left to right and back again and the strip is advanced in a continuous manner, say from right ,0 left, the workrolls 5 and 6, which are separated from each other at their point of nearest approach by a gap substantially equal to the thickness of the reduced strip when in the position shown in FIGURE 1, reduce the strip.

When rolling slabs, the length of the levers 14 and 16 is increased so that the arcs through which the rolls 5 and 6 swing are shifted towards the ingoing side of the mill to a position such that the axes of the rolls 5 and 6 do not reach the centre-line connecting the pivots of the pendulums 12 and 13 during their swing. Some modification of the throw of the cranks and 17 may also be necessary. With such an arrangement there is always a component of the rolling force acting in the direction opposite to the feed of the slab when the pendulums are swinging.

Referring now to FIGURES 2 and 3, the apparatus comprises a framework having upper and lower portions 18, 19. The upper portion 18 has three upper bearings 43. 20, 21 and 22 in which is rotatably-mounted a shaft 23, on which shaft are carried bearings 24 and 25 of a com pound pendulum formed by arms 26, 27, 28 and 29 joined together by a cross-piece 30. The lower end portions of arms 26 and 29 have bearings 31 and 32 in which a work-roll 33 is freely mounted for rotation. The work-roll is backed by three pairs of supporting rollers 34, 34, 35, 35, and 36, 36, which are freely mounted for rotation between arms 26 and 27, 27 and 2S, and 28 and 29 respectively.

The compound pendulum is oscillated from left to right and back again by means of a lever 37 pivotallymounted at 38 at one end to the compound pendulum and pivotally-mounted at the other end to a crank 39 of a crankshaft 40. The crankshaft is driven by any suitable driving means which is not shown in the drawmgs.

The lower portion 19 of the framework has a compound pendulum 41 (which is similar to the compound pendulum formed by arms 26, 27, 28 and 29 and crosspiece 30) mounted on a shaft 42, and having a workroll 43 backed by supporting rollers 47, 48 and 49. The compound pendulum is moved by lever 44 and crank 45 on a crankshaft 46 driven in synchronism by the driving means which drive the crankshaft 40. The screwdown gear in FIGURE 4 is the same as in a similar sized conventional rolling mill and may consist of, for example, a pair of threaded shafts 50 engaging a threaded insert 51 in the framework or housing 52 and bearing on the member 18 to which the arms are pivoted. Each shaft 50 is rotated by means of gears, in this case a worm 53 and worm wheel 54. A strong coil spring 55 is accommodated in a recess 56 in the bottom of the threaded shaft 50 and the recess is closed by a pad 57 bearing on the member 18. The pad 57 is capable of sliding movement within the recess 56 under a load and under the full rolling load the end 58 of the shaft 50 comes into load bearing contact with the member 18. When the rolls 33 and 43, during the rolling opera tion, move slightly past the point of minimum separation in the direction of the reduced strip, the rolling load decreases but under the action of the spring 55, the rolls are maintained in contact with the metal. Omission of the resilient devices requires that there shall be sufficient natural resilience in the mill housing to permit contact to be maintained. In FIGURE 5, the work rolls 33, 43 are shown as provided with opposed flanges 59 to control lateral spread of the metal.

Methods and apparatus in accordance with this invention are particularly suitable for reducing the thickness of titanium or its alloys but they are also suitable for reducing the thickness of other metals. The titanium or the metal to be reduced may be in the form of slab, plate or strip.

I claim:

1. Apparatus for reducing the thickness of metal comprising: frame means; a pair of oppositely swingable arms pivotally mounted to said frame means with their free ends adjacent; a pair of work rolls; means freely rotatably mounting one of said work rolls to the free end of one arm and the other of said rolls to the free end of the other arm, said last-mentioned means constituting the sole means carried by said apparatus in engagement with the ends of said rolls; means for mechanically driving the arms to swing the same forwardly and backwardly in synchronism with each other, and means for positively feeding the metal between said rolls.

2. Apparatus as claimed in claim 1, in which the work-rolls have contoured working surfaces suitable for the production of rolled shapes of crosssection other than rectangular.

3. Apparatus as claimed in claim 1, in which the work-rolls are provided with flanges, the height of which is less than half the thickness of the reduced metal, for engagement with the edges of the metal.

4. Apparatus as claimed in claim 1, and further including means for progressively varying the minimum separation of the work-rolls.

5. Apparatus as claimed in claim 4, in which a resilient device is interposed between the frame and the pivots on which the arms swing.

6. Apparatus according to claim 1 wherein said workrolls are provided with flanges to control the lateral spread of said metal.

7. Apparatus defined in claim 1 including a plurality of freely rotatable backing rolls carried by said frame means in longitudinally spaced relationship opposite to the free ends of each of said arms, and engaged to the respective work rolls to limit deflection thereof.

8. Apparatus defined in claim 7 including two sets of circumferentially spaced apart backing rolls mounted opposite ench of said Work rolls.

9. Apparatus defined in claim 1 including means for adjusting the position of the pivots of said swingable arms relative to said frame means.

References Cited in the file of this patent UNITED STATES PATENTS Inshaw et al June 13, Sommersall Oct. 28, Oberg June 30, McBain May 9, Bennewitz July 11, Dell Mar. 2, Ungerer Apr. 1,

FOREIGN PATENTS Great Britain Feb. 24, Great Britain Feb. 10, Great Britain Feb. 22, Great Britain May 30, Germany Aug. 22, Germany Apr. 5, Great Britain June 1, 

1. APPARATUS FOR REDUCING THE THICKNESS OF METAL COMPRISING; FRAME MEANS; A PAIR OF OPPOSITELY SWINGABLE ARMS PIVOTALLY MOUNTED TO SAID FRAME MEANS WITH THEIR FREE ENDS ADJACENT; A PAIR OF WORK ROLLS; MEANS FREELY ROTATABLY MOUNTING ONE OF SAID WORK ROLLS TO THE FREE END OF ONE ARM AND THE OTHER OF SAID ROLLS TO THE FREE END OF THE OTHER ARM, SAID LAST-MENTIONED MEANS CONSTITUTING THE SOLE MEANS CARRIED BY SAID APPARATUS IN ENGAGEMENT WITH THE ENDS OF SAID ROLLS; MEANS FOR MECHANICALLY DRIVING THE ARMS TO SWING THE SAME FORWARDLY AND BACKWARDLY IN SYNCHRONISM WITH EACH OTHER, AND MEANS FOR POSITIVELY FEEDING THE METAL BETWEEN SAID ROLLS. 